Ex-cop Ted ``Smithy'' Smithfield, the touchy, gallant Venice, Calif., detective in this literate, diverting thriller, has good reason to be suspicious of his beautiful client, fugitive Helen Madden: she's wanted by the feds, the cops and the Mafia. Helen, the resourceful Anglo wife of a Cuban-American accountant, may be innocently mixed up in husband Paco Ortiz's Miami air-conditioning company, ostensibly a front for importing illegal prescription drugs to fight AIDS and cancer. Or she could take stolen millions from the operation, which, it turns out, is actually a government sting to nail Miami banks laundering cocaine money. Does Ortiz know who he's working for? Are his partners--two Sicilian brothers with twin mansions--mobsters or benign eccentrics? Jovanovich, author of a previous novel ( Madmen Must ) and chairman of HBJ, has his gumshoe, and readers, guessing till the end, when Smithy manages even to take revenge on the police captain who sacked him. This puzzler is tough, taut and witty. (Mar.)